142 E. GILPIN ON THE FOLDING OF CARBONIFEROUS STRATA. 
unbroken series into Pictou, where their thickness is estimated by Dr. Dawson at 2,500 feet. 
He also points out that these measures graduate upwards into beds haying a Permian 
aspect, and suggests the term Permo-Carboniferous for their upper portion. In this paper 
they are considered together, as the same remarks apply to both. These beds are also found 
in Prince Edward Island, and extend across the strait to New Brunswick, and are pre- 
sented in shallow synclinals. 
In the Richmond district there is a set of measures which present some evidence of 
unconformability to the horizon holding the Little River coal beds, and may represent the 
upper coal measures. They lie in a shallow basin, and are of limited extent ; their thick- 
ness is about 1,350 feet. 
In the Pictou and Cumberland district these measures are bent in folds, generally with 
low angles, the date of which cannot now be fixed by superimposed strata. The folding of 
the Cape Breton coal field, with its low and broad synclinals is of a similar character, and 
may have been synchronous. It may be considered that these foldings took place before 
the Trias, or toward the close of the Permo-Carboniferous. Since this date the Carboniferous 
measures have undergone some changes of level consequent on the deposition of the Trias, 
and its elevation, and the continental depressions which have left their record in rock 
grooving and travelled boulder. These changes, however, except locally, in the case of the 
Trias of the Bay of Fundy, do not appear to have greatly affected the Carboniferous, for we 
find the interior of New Brunswick, the Millstone Grit of Dorchester, the Upper Coal 
Measures and Permo-Carboniferous of Cumberland, Pictou, and Prince Edward Island 
lying in positions indicating slight movements, except those of a continental character. 
Prior to the opening of the Carboniferous period the rocks of Nova Scotia were folded 
in regular east and west folds which have been explored and mapped in the iron ore and 
gold-bearing districts, and the regularity of their folds and other evidence would tend to 
show that they have not been greatly disturbed since that date. The Carboniferous 
measures were unconformably deposited on these strata, and their long period permitted a 
maximum accumulation of strata reaching 22,000 feet. 
During this time, in addition to the continental changes of level, giving rise to condi- 
tions of deposition characterizing the Carboniferous limestone, Millstone Grit, etc., there 
were extensive foldings of a more local character, apparently in some cases marking the 
closing of these oscillations. These foldings and their subsequent denudations have 
played an important part, hitherto but little studied, in modifying the conditions arising 
from the longer and more extended movements which have hitherto principally received 
attention, and present the district as being far from any universal state of quiet and 
regular succession during the Carboniferous era. 

